U.S. patent number 10,439,742 [Application Number 15/577,739] was granted by the patent office on 2019-10-08 for device and method for performing channel decoding operation in communication system.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Sung-Nam Hong, Tae-Young Kim, Min Sagong, Ji-Yun Seol.
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United States Patent |
10,439,742 |
Hong , et al. |
October 8, 2019 |
Device and method for performing channel decoding operation in
communication system
Abstract
The present invention relates to not only a 4th-generation (4G)
communication system such as long term evolution (LTE), but also a
5th-generation (5G) or pre-5G communication system which is
provided to support a higher data rate. The present invention
provides a method for performing a channel decoding operation by a
reception device in a communication system, the method comprising
the steps of: generating at least two resource elements (REs) into
at least two RE groups; and generating a soft decision decoding
metric for a signal received through each of the at least two RE
groups.
Inventors: |
Hong; Sung-Nam (Anyang-si,
KR), Kim; Tae-Young (Seongnam-si, KR),
Sagong; Min (Suwon-si, KR), Seol; Ji-Yun
(Seongnam-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Gyeonggi-do |
N/A |
KR |
|
|
Assignee: |
Samsung Electronics Co., Ltd.
(Suwon-si, KR)
|
Family
ID: |
57573848 |
Appl.
No.: |
15/577,739 |
Filed: |
May 27, 2016 |
PCT
Filed: |
May 27, 2016 |
PCT No.: |
PCT/KR2016/005649 |
371(c)(1),(2),(4) Date: |
November 28, 2017 |
PCT
Pub. No.: |
WO2016/190710 |
PCT
Pub. Date: |
December 01, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180131454 A1 |
May 10, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Jun 11, 2015 [KR] |
|
|
10-2015-0082858 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0048 (20130101); H04B 17/318 (20150115); H04L
1/0045 (20130101); H04L 25/067 (20130101); H04L
25/03968 (20130101); H04L 25/03184 (20130101); H04L
5/0007 (20130101); H04L 1/0048 (20130101) |
Current International
Class: |
H04B
17/318 (20150101); H04L 5/00 (20060101); H04L
1/00 (20060101); H04L 25/03 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Soret et al.; "CRS Interference Cancellation in Heterogeneous
Networks for LTE-Advanced Downlink"; 2012 IEEE International
Conference on Communications (ICC); Ottawa, Ontario, Canada; Jun.
10-15, 2012; 5 pages. cited by applicant .
Davydov et al.; "LLR-based Interference Suppression for the
Physical Downlink Control Channel of LTE-A"; 2014 IEEE Annual
International Symposium on Personal, Indoor, and Mobile Radio
Communication (PIMRC); Washington, D.C., USA; Sep. 2-5, 2014; 6
pages. cited by applicant.
|
Primary Examiner: Haider; Syed
Claims
The invention claimed is:
1. A method for channel decoding by a user equipment (UE) in a
communication system, the method comprising: generating at least
two resource element (RE) groups including at least two REs,
wherein the at least two RE groups includes a first RE group that
is affected by an interference signal and a second RE group that is
not affected by the interference signal; canceling, a target signal
of a serving base station, from a received signal that corresponds
to the first RE group and canceling the target signal from a
received signal that corresponds to the second RE group; and
generating a decoding metric for the received signal that
corresponds to the first RE group based on a signal generated by
canceling the target signal from the received signal that
corresponds to the first RE group and generating a decoding metric
for the received signal that corresponds to the second RE group
based on a signal generated by canceling the target signal from the
received signal that corresponds to the second RE group.
2. The method of claim 1, wherein the generating the at least two
RE groups comprises: generating the at least two REs as the at
least two RE groups is based on an interference characteristic.
3. The method of claim 1, wherein the generating the at least two
RE groups comprises: generating the at least two RE groups that
includes an RE group including at least one RE that is not affected
by an interference signal and an RE group including at least one RE
that is affected by the interference signal.
4. The method of claim 1, further comprising: receiving information
related to an interference signal from a base station, wherein the
information related to the interference signal includes information
related to a reference signal transmitted from other base
station.
5. The method of claim 1, wherein the decoding metric includes: a
soft decision decoding metrics corresponding to the first RE group
and the second RE group.
6. The method of claim 1, wherein generating the decoding metric
comprises: estimating a soft decision decoding metric parameter for
each of the signal generated by canceling the target signal from
the received signal that corresponds to the first RE group and the
signal generated by canceling the target signal from the received
signal that corresponds to the second RE group; and canceling the
target signal from the received signal that corresponds to the
first RE group, and calculating a soft decision decoding metric for
the received signal that corresponds to the second RE group based
on the soft decision decoding metric parameter that is estimated
for the signal generated by canceling the target signal from the
received signal that corresponds to the second RE group.
7. A user equipment (UE) for channel decoding in a communication
system, the UE comprising: a transceiver configured to communicate
with a base station; and a processor coupled with the transceiver
and configured to: generate at least two resource element (RE)
groups including at least two REs, wherein the at least two RE
groups includes a first RE group that is affected by an
interference signal and a second RE group that is not affected by
the interference signal, cancel, a target signal of a serving base
station, from a received signal that corresponds to the first RE
group and canceling the target signal from a received signal that
corresponds to the second RE group, and generate a decoding metric
for the received signal that corresponds to the first RE group
based on a signal generated by canceling the target signal from the
received signal that corresponds to the first RE group and
generating a decoding metric for the received signal that
corresponds to the second RE group based on a signal generated by
canceling the target signal from the received signal that
corresponds to the second RE group.
8. The UE of claim 7, wherein the processor further configured to:
generate the at least two REs as the at least two RE groups that
includes an RE group including at least one RE that is not affected
by an interference signal and an RE group including at least one RE
that is affected by the interference signal.
9. The UE of claim 7, wherein the processor further configured to:
receive information related to an interference signal from a base
station, wherein the information related to the interference signal
includes information related to a reference signal transmitted from
other base station.
10. The UE of claim 7, wherein the decoding metric includes a soft
decision decoding metrics corresponding to the first RE group and
the second RE group.
11. The UE of claim 7, wherein the processor is further configured
to: estimate a soft decision decoding metric parameter for each of
the signal generated by canceling the target signal from the
received signal that corresponds to the first RE group and the
signal generated by canceling the target signal from the received
signal that corresponds to the second RE group; and calculate a
soft decision decoding metric for the received signal that
corresponds to the first RE group based on the soft decision
decoding metric parameter that is estimated for the signal
generated by canceling the target signal from the received signal
that corresponds to the first RE group, and calculate a soft
decision decoding metric for the received signal that corresponds
to the second RE group based on the soft decision decoding metric
parameter that is estimated for the signal generated by canceling
the target signal from the received signal that corresponds to the
second RE group.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY
This application is a U.S. National Stage application under 35
U.S.C. .sctn. 371 of an International application filed on May 27,
2016 and assigned application number PCT/KR2016/005649, which
claimed the benefit of Korean patent applications Nos.
10-2015-0074835 and 10-2015-0082858 filed on May 28, 2015 and Jun.
11, 2015, the entire disclosures of each of which are hereby
incorporated by reference.
TECHNICAL FIELD
The present disclosure relates to an apparatus and method for
performing a channel decoding operation in a communication system,
and more particularly, to an apparatus and method for performing a
channel decoding operation by considering interference.
BACKGROUND
To meet the demand for wireless data traffic, which has increased
since deployment of 4th-generation (4G) communication systems,
efforts have been made to develop an improved 5th-generation (5G)
or pre-5G communication system. Therefore, the 5G or pre-5G
communication system is also called a `beyond 4G network` or a
`post long-term evolution (LTE) system`.
It is considered that the 5G communication system will be
implemented in millimeter wave (mmWave) bands, e.g., 60 GHz bands,
so as to accomplish higher data rates. To reduce propagation loss
of radio waves and increase a transmission distance, a beam forming
technique, a massive multiple-input multiple-output (MIMO)
technique, a full dimensional MIMO (FD-MIMO) technique, an array
antenna technique, an analog beam forming technique, and a large
scale antenna technique are discussed in 5G communication
systems.
In addition, in 5G communication systems, development for system
network improvement is under way based on advanced small cells,
cloud radio access networks (RANs), ultra-dense networks, a
device-to-device (D2D) communication, a wireless backhaul, a moving
network, a cooperative communication, coordinated multi-points
(CoMP), reception-end interference cancellation, and the like.
In the 5G system, a hybrid frequency shift keying (FSK) and
quadrature amplitude modulation (QAM) modulation (FQAM) and a
sliding window superposition coding (SWSC) as an advanced coding
modulation (ACM) scheme, and a filter bank multi carrier (FBMC)
scheme, a non-orthogonal multiple Access (NOMA) scheme, and a
sparse code multiple access (SCMA) scheme as an advanced access
technology have been developed.
In a downlink/uplink of a communication system supporting an
orthogonal frequency division multiple access (OFDMA) scheme,
inter-cell interference (ICI) may significantly degrade performance
of a signal receiving apparatus. Particularly, if a reference
signal, e.g., a pilot signal, which is used for the signal
receiving apparatus to estimate a channel or to measure a channel
is distorted due to influence of the ICI, the performance of the
signal receiving apparatus may be significantly degraded.
So, most communication standards supporting an OFDMA scheme, e.g.,
an LTE use various schemes, e.g., a scheme of differently setting
location of a reference signal used in each of cells, a scheme of
power boosting a reference signal compared to a data signal, e.g.,
a data symbol and transmitting the power boosted reference signal,
and/or the like.
For example, a downlink of an LTE mobile communication system
defines that neighbor base stations shift cell-specific reference
signals (CRSs) from a specific CRC on a frequency axis based on
different offsets and transmit the shifted CRSs, and each base
station may power boost a corresponding CRS using a transmission
power greater than transmission power applied to a data signal to
transmit the power boosted CRS.
The schemes as described above may decrease a degree of distortion
of a reference signal due to ICI thereby preventing relatively
large degradation of channel estimation performance and channel
measurement performance of a signal receiving apparatus.
However, the power boosted reference signal as described above
becomes ICI for a data signal included in a target signal, so a
non-Gaussian characteristic of an interference signal occurs due to
this. This will be described with reference to FIGS. 1 and 2.
Firstly, relation among an interference signal, a target signal,
and a received signal in a general LTE mobile communication system
will be described with reference to FIG. 1.
FIG. 1 schematically illustrates relation among an interference
signal, a target signal, and a received signal in a general LTE
mobile communication system.
Referring to FIG. 1, it will be noted that an interference signal,
a target signal, and a received signal in FIG. 1 are shown on a
resource block (RB) unit basis. Here, an RB includes at least one
resource element (RE).
An interference signal 111 denotes a signal transmitted from a
neighbor cell, and the interference signal 111 includes, for
example, a physical downlink control channel (PDCCH) signal and a
CRS transmitted from the neighbor cell.
Further, a target signal 113 denotes a signal transmitted from a
corresponding cell, and the target signal 113 includes, for
example, a PDCCH signal and a CRS transmitted from the
corresponding cell.
Meanwhile, a received signal 115 denotes a signal which a
corresponding signal receiving apparatus, e.g., a user equipment
(UE) receives, and the received signal 115 includes the PDCCH
signal and CRS included in the target signal 113 and the PDCCH
signal and CRS included in the reference signal 111.
In the LTE mobile communication system, location of CRSs is
differently set among neighbor cells, so specific REs among REs
included in an RB through which the target signal 113 is
transmitted may be affected by the CRS included in the interference
signal 111, and may be further affected by a PDSCH included in the
interference signal 111 according to a situation.
Relation among an interference signal, a target signal, and a
received signal in a general LTE mobile communication system has
been described with reference to FIG. 1, and ICI distribution for
an RE group affected by an interference CRS in a general LTE mobile
communication system will be described with reference to FIG.
2.
FIG. 2 schematically illustrates ICI distribution for an RE group
affected by an interference CRS in a general LTE mobile
communication system.
Referring to FIG. 2, an ICI distribution graph as shown in FIG. 2
indicates an ICI distribution graph for an RE group in a case that
a signal receiving apparatus, e.g., a UE uses one antenna port, and
the number of neighbor cells is 1. In the ICI distribution graph as
shown in FIG. 2, a vertical axis indicates a histogram of ICI, and
a horizontal axis indicates a real part of the ICI.
Generally, a CRS is boosted with power which is greater than power
applied to a data signal by a preset value, e.g., 12 [dB]. So, a
CRS transmitted from a neighbor cell may act as ICI for specific
REs among REs included in an RB, i.e., target RB, through a target
signal of a corresponding cell is transmitted, so a non-Gaussian of
an interference signal occurs due to this.
As illustrated in FIG. 2, it will be understood that ICI 213 for a
data region shows a Gaussian characteristic, and ICI 211 for a CRS
region shows a non-Gaussian characteristic. In FIG. 2, a reference
number 215 indicates a Gaussian probability density function
(PDF).
ICI distribution for an RE group affected by an interference CRS in
a general LTE mobile communication system has been described with
reference to FIG. 2, and a process of performing a channel decoding
operation in a signal receiving apparatus in an interference
environment with a non-Gaussian characteristic in a general LTE
mobile communication system will be described with reference to
FIG. 3.
FIG. 3 schematically illustrates a process of performing a channel
decoding operation in a signal receiving apparatus in an
interference environment with a non-Gaussian characteristic in a
general LTE mobile communication system.
Referring to FIG. 3, a signal receiving apparatus calculates an LLR
for a received signal at operation 311, and this will be described
below.
The signal receiving apparatus detects a data signal which is
affected by a target reference signal from the received signal at
operation 313, and proceeds to operation 315. Here, the target
reference signal denotes a reference signal transmitted from a cell
to which the signal receiving apparatus belongs, i.e., a serving
cell. The signal receiving apparatus cancels a component related to
the target reference signal from the data signal which is affected
by the target reference signal at operation 315, and proceeds to
operation 317.
The signal receiving apparatus estimates variance of noise which is
affected by ICI based on the target reference signal at operation
317, and proceeds to operation 311. The signal receiving apparatus
applies a Gaussian PDF based on the estimated variance of the noise
to calculate a soft decision decoding metric, e.g., a
log-likelihood ratio (LLR) for the received signal at operation
311.
The channel decoding operation of the signal receiving apparatus as
described in FIG. 3 is a channel decoding operation in a case that
the signal receiving apparatus may not receive location information
for a reference signal transmitted from a neighbor cell.
As described above, currently in most communication standards
supporting an OFDMA scheme, location of reference signals used in
neighbor cells is differently set, so influence of a power boosted
interference reference signal is not reflected in the received
target reference signal.
So, a channel decoding operation using an LLR calculated based on a
scheme as described in FIG. 3 may not reflect influence of power
boosted interference reference signal, so the channel decoding
operation may significantly degrade channel decoding performance of
a signal receiving apparatus.
The above information is presented as background information only
to assist with an understanding of the present disclosure. No
determination has been made, and no assertion is made, as to
whether any of the above might be applicable as prior art with
regard to the present disclosure.
SUMMARY
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation in a
communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation based on RE
grouping in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation using a
plurality of soft decision decoding metric generating schemes in a
communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference regardless of whether location information for an
interference reference signal is provided in a communication
system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference based on RE grouping in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering a
Gaussian characteristic of an interference signal and a
non-Gaussian characteristic of the interference signal in a
communication system.
According to an embodiment of the present disclosure, a method for
performing a channel decoding operation by a receiving apparatus in
a communication system is provided. The method includes generating
at least two resource elements (REs) as at least two RE groups, and
generating a soft decision decoding metric for a signal received
through each of the at least two RE groups.
According to an embodiment of the present disclosure, an operating
method of a transmitting apparatus in a communication system is
provided. The operating method includes transmitting, to a
receiving apparatus, information related to an interference signal,
wherein the information related to the interference signal is used
for the receiving apparatus to perform an operation of generating
at least two resource elements (REs) as at least two RE groups, and
an operation of generating a soft decision decoding metric for a
signal received through each of the at least two RE groups.
According to an embodiment of the present disclosure, a receiving
apparatus in a communication system is provided. The receiving
apparatus includes a soft decision decoding metric generator
configured to perform an operation of generating at least two
resource elements (REs) as at least two RE groups, and to perform
an operation of generating a soft decision decoding metric for a
signal received through each of the at least two RE groups.
According to an embodiment of the present disclosure, a
transmitting apparatus in a communication system is provided. The
transmitting apparatus includes a transmitter configured to
transmit, to a receiving apparatus, information related to an
interference signal, wherein the information related to the
interference signal is used for the receiving apparatus to perform
an operation of generating at least two resource elements (REs) as
at least two RE groups, and an operation of generating a soft
decision decoding metric for a signal received through each of the
at least two RE groups.
Other aspects, advantages, and salient features of the disclosure
will become apparent to those skilled in the art from the following
detailed description, which, taken in conjunction with the annexed
drawings, discloses exemplary embodiments of the disclosure.
Before undertaking the DETAILED DESCRIPTION below, it may be
advantageous to set forth definitions of certain words and phrases
used throughout this patent document: the terms "include" and
"comprise," as well as derivatives thereof, mean inclusion without
limitation; the term "or," is inclusive, meaning and/or; the
phrases "associated with" and "associated therewith," as well as
derivatives thereof, may mean to include, be included within,
interconnect with, contain, be contained within, connect to or
with, couple to or with, be communicable with, cooperate with,
interleave, juxtapose, be proximate to, be bound to or with, have,
have a property of, or the like; and the term "controller" means
any device, system or part thereof that controls at least one
operation, such a device may be implemented in hardware, firmware
or software, or some combination of at least two of the same. It
should be noted that the functionality associated with any
particular controller may be centralized or distributed, whether
locally or remotely. Definitions for certain words and phrases are
provided throughout this patent document, those of ordinary skill
in the art should understand that in many, if not most instances,
such definitions apply to prior, as well as future uses of such
defined words and phrases.
An embodiment of the present disclosure enables to perform a
channel decoding operation in a communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation based on resource element (RE) grouping
in a communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation using a plurality of soft decision
decoding metric generating schemes in a communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation by considering interference in a
communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation by considering interference regardless
of whether location information for an interference reference
signal is provided in a communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation by considering interference based on RE
grouping in a communication system.
An embodiment of the present disclosure enables to perform a
channel decoding operation by considering a Gaussian characteristic
of an interference signal and a non-Gaussian characteristic of the
interference signal in a communication system.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects, features and advantages of certain
exemplary embodiments of the present disclosure will be more
apparent from the following description taken in conjunction with
the accompanying drawings, in which:
FIG. 1 schematically illustrates relation among an interference
signal, a target signal, and a received signal in a general LTE
mobile communication system;
FIG. 2 schematically illustrates ICI distribution for an RE group
affected by an interference CRS in a general LTE mobile
communication system;
FIG. 3 schematically illustrates a process of performing a channel
decoding operation in a signal receiving apparatus in an
interference environment with a non-Gaussian characteristic in a
general LTE mobile communication system;
FIG. 4 schematically illustrates an example of an inner structure
of a signal transmitting apparatus in a communication system
supporting an orthogonal frequency division multiple access (OFDMA)
scheme according to an embodiment of the present disclosure;
FIG. 5 schematically illustrates an example of an inner structure
of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 6 schematically illustrates an example of a process of
generating a soft decision decoding metric in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 7 schematically illustrates another example of a process of
generating a soft decision decoding metric in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIGS. 8A and 8B schematically illustrate an example of a process of
performing an RE grouping process in a signal receiving apparatus
in a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure;
FIGS. 9A to 9C schematically illustrate another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 10 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 11 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 12 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 13 schematically illustrates an example of a CRS structure
according to the number of CRS ports in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 14 schematically illustrates another example of a CRS
structure according to the number of CRS ports in a communication
system supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 15 schematically illustrates still another example of a CRS
structure according to the number of CRS ports in a communication
system supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 16 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 17 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure;
FIG. 18 schematically illustrates performance in a case that an RE
grouping process is applied in a communication system supporting an
OFDMA scheme according to an embodiment of the present
disclosure;
FIG. 19 schematically illustrates another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 20 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure;
FIG. 21 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure; and
FIG. 22 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
FIG. 23 schematically illustrates the generated LLR to the channel
decoder 2221.
Throughout the drawings, it should be noted that like reference
numbers are used to depict the same or similar elements, features,
and structures.
DETAILED DESCRIPTION
The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
various embodiments of the present disclosure as defined by the
claims and their equivalents. It includes various specific details
to assist in that understanding but these are to be regarded as
merely exemplary. Accordingly, those of ordinary skill in the art
will recognize that various changes and modifications of the
various embodiments described herein can be made without departing
from the scope and spirit of the present disclosure. In addition,
descriptions of well-known functions and constructions may be
omitted for clarity and conciseness.
The terms and words used in the following description and claims
are not limited to the bibliographical meanings, but, are merely
used by the inventor to enable a clear and consistent understanding
of the present disclosure. Accordingly, it should be apparent to
those skilled in the art that the following description of various
embodiments of the present disclosure is provided for illustration
purpose only and not for the purpose of limiting the present
disclosure as defined by the appended claims and their
equivalents.
It is to be understood that the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates
otherwise. Thus, for example, reference to "a component surface"
includes reference to one or more of such surfaces.
Although ordinal numbers such as "first," "second," and so forth
will be used to describe various components, those components are
not limited herein. The terms are used only for distinguishing one
component from another component. For example, a first component
may be referred to as a second component and likewise, a second
component may also be referred to as a first component, without
departing from the teaching of the inventive concept. The term
"and/or" used herein includes any and all combinations of one or
more of the associated listed items.
The terminology used herein is for the purpose of describing
various embodiments only and is not intended to be limiting. As
used herein, the singular forms are intended to include the plural
forms as well, unless the context clearly indicates otherwise. It
will be further understood that the terms "comprises" and/or "has,"
when used in this specification, specify the presence of a stated
feature, number, step, operation, component, element, or
combination thereof, but do not preclude the presence or addition
of one or more other features, numbers, steps, operations,
components, elements, or combinations thereof.
The terms used herein, including technical and scientific terms,
have the same meanings as terms that are generally understood by
those skilled in the art, as long as the terms are not differently
defined. It should be understood that terms defined in a
generally-used dictionary have meanings coinciding with those of
terms in the related technology.
According to various embodiments of the present disclosure, an
electronic device may include communication functionality. For
example, an electronic device may be a smart phone, a tablet
personal computer (PC), a mobile phone, a video phone, an e-book
reader, a desktop PC, a laptop PC, a netbook PC, a personal digital
assistant (PDA), a portable multimedia player (PMP), an mp3 player,
a mobile medical device, a camera, a wearable device (e.g., a
head-mounted device (HMD), electronic clothes, electronic braces,
an electronic necklace, an electronic appcessory, an electronic
tattoo, or a smart watch), and/or the like.
According to various embodiments of the present disclosure, an
electronic device may be a smart home appliance with communication
functionality. A smart home appliance may be, for example, a
television, a digital video disk (DVD) player, an audio, a
refrigerator, an air conditioner, a vacuum cleaner, an oven, a
microwave oven, a washer, a dryer, an air purifier, a set-top box,
a TV box (e.g., Samsung HomeSync.TM., Apple TV.TM., or Google
TV.TM.), a gaming console, an electronic dictionary, an electronic
key, a camcorder, an electronic picture frame, and/or the like.
According to various embodiments of the present disclosure, an
electronic device may be a medical device (e.g., magnetic resonance
angiography (MRA) device, a magnetic resonance imaging (MRI)
device, computed tomography (CT) device, an imaging device, or an
ultrasonic device), a navigation device, a global positioning
system (GPS) receiver, an event data recorder (EDR), a flight data
recorder (FDR), an automotive infotainment device, a naval
electronic device (e.g., naval navigation device, gyroscope, or
compass), an avionic electronic device, a security device, an
industrial or consumer robot, and/or the like.
According to various embodiments of the present disclosure, an
electronic device may be furniture, part of a building/structure,
an electronic board, electronic signature receiving device, a
projector, various measuring devices (e.g., water, electricity, gas
or electro-magnetic wave measuring devices), and/or the like that
include communication functionality.
According to various embodiments of the present disclosure, an
electronic device may be any combination of the foregoing devices.
In addition, it will be apparent to one having ordinary skill in
the art that an electronic device according to various embodiments
of the present disclosure is not limited to the foregoing
devices.
According to various embodiments of the present disclosure, a
signal receiving apparatus may be, for example, a user equipment
(UE), and a signal transmitting apparatus may be, for example, a
base station.
In various embodiments of the present disclosure, it will be noted
that the term UE may be interchangeable with the terms mobile
station (MS), wireless terminal, mobile device, and/or the
like.
In various embodiments of the present disclosure, it will be noted
that the term base station may be interchangeable with the terms
node B, evolved Node B (eNB), access point (AP), and/or the
like.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation in a
communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation based on
resource element (RE) grouping in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation using a
plurality of soft decision decoding metric generating schemes in a
communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference regardless of whether location information for an
interference reference signal is provided in a communication
system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering
interference based on RE grouping in a communication system.
An embodiment of the present disclosure proposes an apparatus and
method for performing a channel decoding operation by considering a
Gaussian characteristic of an interference signal and a
non-Gaussian characteristic of the interference signal in a
communication system.
An apparatus and method proposed in various embodiments of the
present disclosure may be applied to various communication systems
such as a long term evolution (LTE) mobile communication system, an
LTE-advanced (LTE-A) mobile communication system, a
licensed-assisted access (LAA)-LTE mobile communication system, a
high speed downlink packet access (HSDPA) mobile communication
system, a high speed uplink packet access (HSUPA) mobile
communication system, a high rate packet data (HRPD) mobile
communication system proposed in a 3rd generation partnership
project 2 (3GPP2), a wideband code division multiple access (WCDMA)
mobile communication system proposed in the 3GPP2, a code division
multiple access (CDMA) mobile communication system proposed in the
3GPP2, an institute of electrical and electronics engineers (IEEE)
802.16m communication system, an evolved packet system (EPS), and a
mobile internet protocol (Mobile IP) system, and/or the like.
An example of an inner structure of a signal transmitting apparatus
in a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure will be described with
reference to FIG. 4.
FIG. 4 schematically illustrates an example of an inner structure
of a signal transmitting apparatus in a communication system
supporting an orthogonal frequency division multiple access (OFDMA)
scheme according to an embodiment of the present disclosure.
Referring to FIG. 4, a signal transmitting apparatus 400 may be,
for example, a base station, and includes a channel encoder 411, a
modulator 413, and a transmitter 415.
When information is inputted, the channel encoder 411 generates
encoded bits by channel encoding the information based on a preset
channel encoding scheme, and outputs the generated encoded-bits to
the modulator 413. Here, the encoded bits may be, for example, one
of a binary channel code. The binary channel code may be, for
example, one of a convolutional code, a turbo code, a low density
parity check (LDPC), and/or the like.
The modulator 413 generates the encoded bits outputted from the
channel encoder 411 based on a preset modulation scheme, e.g., a
quadrature phase shift keying (QPSK) scheme to generate a
modulation symbol, and outputs the modulation symbol to the
transmitter 415.
The transmitter 415 performs a transmission signal processing on
the modulation symbol outputted from the modulator 413 to output
the transmission signal processed-signal to a signal receiving
apparatus, e.g., a UE. The transmitter 415 transmits information
related to an interference signal, the information related to the
interference signal will be described below, and a detailed
description thereof will be omitted herein.
Although the channel encoder 411, the modulator 413, and the
transmitter 415 are described as separate units in the signal
transmitting apparatus 400 in FIG. 4, it is to be understood that
the signal transmitting apparatus 400 may be implemented with a
form into which at least two of the channel encoder 411, the
modulator 413, and the transmitter 415 are incorporated. The signal
transmitting apparatus 400 may be implemented with one
processor.
An example of an inner structure of a signal transmitting apparatus
in a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure has been described with
reference to FIG. 4, and an example of an inner structure of a
signal receiving apparatus in a communication system supporting an
OFDMA scheme according to an embodiment of the present disclosure
will be described with reference to FIG. 5.
FIG. 5 schematically illustrates an example of an inner structure
of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 5, a signal receiving apparatus 500 may be, for
example, a UE, and includes a receiver 511, a soft decision
decoding metric generator 513, and a channel decoder 515.
The receiver 511 receives a signal transmitted from a signal
transmitting apparatus through a channel, and outputs the received
signal to the soft decision decoding metric generator 513.
The soft decision decoding metric generator 513 detects a soft
decision decoding metric, e.g., a reliability value for the
received signal to output the soft decision decoding metric to the
channel decoder 515. For example, in a case that a QPSK modulation
scheme is applied, the soft decision decoding metric generator 513
inputs one received symbol in a form of one complex value, and
detects a reliability value for two bits based on this. Here, the
reliability value may be, for example, a log-likelihood ratio
(LLR), so the soft decision decoding metric generator 513 may be
referred to as LLR generator.
The soft decision decoding metric generator 513 may perform an RE
grouping process according to an embodiment of the present
disclosure to generate RE groups, and separately applies a soft
decision decoding metric generating scheme, e.g., a Gaussian
probability density function (PDF) or a non-Gaussian PDF to each of
the RE groups to detect a soft decision decoding metric. A typical
one of the non-Gaussian PDF is a complex-generalized Gaussian (CGG)
PDF, and/or the like. The RE grouping process and the soft decision
decoding metric detecting operation which the soft decision
decoding metric generator 513 performs will be described below, and
a detailed description thereof will be omitted herein.
The channel decoder 515 performs a channel decoding operation which
corresponds to a preset channel decoding scheme based on the
reliability value outputted from the soft decision decoding metric
generator 513 to generate decoded bits, and outputs the decoded
bits.
Although the receiver 511, the soft decision decoding metric
generator 513, and the channel decoder 515 are described as
separate units in the signal receiving apparatus 500 in FIG. 5, it
is to be understood that the signal receiving apparatus 500 may be
implemented with a form into which at least two of the receiver
511, the soft decision decoding metric generator 513, and the
channel decoder 515 are incorporated. The signal receiving
apparatus 500 may be implemented with one processor.
An example of an inner structure of a signal receiving apparatus in
a communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure has been described with
reference to FIG. 5, and an example of a process of generating a
soft decision decoding metric in a signal receiving apparatus in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure will be described with
reference to FIG. 6.
FIG. 6 schematically illustrates an example of a process of
generating a soft decision decoding metric in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 6, it will be noted that a process of generating
a soft decision decoding metric in a signal receiving apparatus as
shown in FIG. 6 is a process of generating a soft decision decoding
metric in a signal receiving apparatus in a case that location
information for an interference reference signal which may be
inter-cell interference (ICI) is provided. Here, an interference
reference signal denotes a reference signal transmitted by a
neighbor base station, not a base station, i.e., a serving base
station, to which a corresponding signal receiving apparatus, e.g.,
a UE currently belongs. For convenience, the reference signal
transmitted by the serving base station will be referred to as
target reference signal.
When a received signal is inputted, the signal receiving apparatus
determines whether location of sub-carriers to which the received
signal is mapped is identical to location of sub-carriers to which
an interference reference signal is mapped at operation 611. If the
location of the sub-carriers to which the received signal is mapped
is not identical to the location of the sub-carriers to which the
interference reference signal is mapped, the signal receiving
apparatus proceeds to operation 619. If the location of the
sub-carriers to which the received signal is mapped is identical to
the location of the sub-carriers to which the interference
reference signal is mapped, the signal receiving apparatus proceeds
to operation 627.
Meanwhile, the signal receiving apparatus detects a data signal
which is affected by a target reference signal from the received
signal at operation 613, and proceeds to operation 615. The signal
receiving apparatus cancels a component related to the target
reference signal from the data signal which is affected by the
target reference signal at operation 615, and proceeds to operation
617. The signal receiving apparatus estimates noise variance for a
data signal from which the component related to the target
reference signal is canceled at operation 617, and proceeds to
operation 619. A detailed description of an operation of estimating
the noise variance will be omitted herein. The signal receiving
apparatus calculates a soft decision decoding metric, i.e., an LLR
based on the noise variance which is estimated for the data signal
from which the component related to the target reference signal is
canceled at operation 619.
Meanwhile, the signal receiving apparatus detects a data signal
which is affected by an interference reference signal from the
received signal at operation 621, and proceeds to operation 623.
The signal receiving apparatus cancels a component related to a
target data signal from the data signal which is affected by the
interference reference signal at operation 623, and proceeds to
operation 625. Here, the target data signal denotes a data signal
actually transmitted by a signal transmitting apparatus, and has
been estimated already by the signal receiving apparatus.
The signal receiving apparatus estimates noise variance for a data
signal from which the component related to the target data signal
is canceled at operation 625, and proceeds to operation 627. A
detailed description of an operation of estimating the noise
variance will be omitted herein. The signal receiving apparatus
calculates a soft decision decoding metric, i.e., an LLR based on
the noise variance which is estimated for the data signal from
which the component related to the target data signal is canceled
at operation 627.
Although FIG. 6 illustrates an example of a process of generating a
soft decision decoding metric in a signal receiving apparatus in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure, various changes could be made
to FIG. 6. For example, although shown as a series of operations,
various operations in FIG. 6 could overlap, occur in parallel,
occur in a different order, or occur multiple times.
As described in FIG. 6, if it is possible that a signal receiving
apparatus receives location information for an interference
reference signal, the a signal receiving apparatus calculates an
LLR based on noise variance for a data signal affected by a target
reference signal and noise variance for a data signal affected by
an interference reference signal.
In a case of calculating an LLR like this, the signal receiving
apparatus needs to estimate the target data signal in order to
estimate the noise variance for the data signal affected by the
interference reference signal, an error may occur upon estimating
the target data signal.
The signal receiving apparatus separately estimates noise variance
based on only a data signal which is affected by an interference
signal, so the number of samples used for estimating the noise
variance is not sufficient. In this case, error may occur upon
estimating noise variance since the number of samples is not
sufficient.
So, an embodiment of the present disclosure proposes a scheme which
may generate a soft decision decoding metric regardless of whether
a signal receiving apparatus may receive location information for
an interference reference signal.
Another example of a process of generating a soft decision decoding
metric in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 7.
FIG. 7 schematically illustrates another example of a process of
generating a soft decision decoding metric in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 7, it will be noted that a process of generating
a soft decision decoding metric in a signal receiving apparatus as
shown in FIG. 7 is a process of generating a soft decision decoding
metric in a signal receiving apparatus regardless of whether
location information for an interference reference signal is
provided to the signal receiving apparatus.
When a received signal is inputted, the signal receiving apparatus
determines whether sub-carries to which the received signal is
mapped are included in a group#1 at operation 711. If the
sub-carries to which the received signal is mapped are included in
the RE group#1, the signal receiving apparatus proceeds to
operation 719. If the sub-carries to which the received signal is
mapped are not included in the RE group#1, that is, if the
sub-carries to which the received signal is mapped are included in
an RE group#2, the signal receiving apparatus proceeds to operation
727.
Each of the RE group#1 and the RE group#1 will be described
below.
An RE group includes at least one RE, and an RE may be, for
example, a sub-carrier. In an embodiment of the present disclosure,
the communication system supports the OFDMA scheme, so it has been
assumed that the RE is, for example, the sub-carrier, however, if
the communication system does not support the OFDMA scheme, the RE
may be a resource in a different form, not the sub-carrier.
The RE group#1 includes REs, and a signal received through the REs
is not affected by a boosted interference signal. Here, the boosted
interference signal may be, for example, a target reference signal,
an interference reference signal, and/or the like.
The RE group#2 includes REs, and there is a possibility that a
signal received through the REs is affected by a boosted
interference signal.
For example, in a case of a downlink in an LTE mobile communication
system, location of sub-carriers through which a cell-specific
reference signal (CRS) is transmitted is determined based on a cell
identifier (ID) of a corresponding cell, and the location of the
sub-carriers through which the CRS is transmitted is determined
based on a limited pattern.
So, a signal receiving apparatus, e.g., a UE may detect
sub-carriers which is likely to be affected by a CRS, and these
sub-carriers may be included in the RE group#2. That is,
sub-carriers which are mapped to a CRS transmitted by a serving
cell to which a UE currently belongs, i.e., a target CRS and
sub-carriers which are mapped to a CRS transmitted by a neighbor
cell, i.e., an interference CRS may be included in the RE
group#2.
An RE grouping process of generating the RE group#1 and the RE
group#2 will be described below, so a detailed description thereof
will be omitted herein.
Meanwhile, the signal receiving apparatus detects a received signal
which corresponds to the RE group #1 from the received signal at
operation 713, and proceeds to operation 715. For convenience, the
received signal corresponding to the RE group #1 will be referred
to as `RE group #1-received signal`. The signal receiving apparatus
cancels a target data signal from an RE group #1-received signal at
operation 715, and proceeds to operation 717. The target data
signal denotes a data signal actually transmitted by a signal
transmitting apparatus, and has been estimated already by the
signal receiving apparatus. Particularly, there are no REs through
a CRS is transmitted in the RE group #1, so there is no reference
signal used for estimating a statistical characteristic of
interference and noise variance. So, the signal receiving apparatus
performs a hard decision operation or a soft decision operation on
a received signal in advance to estimate the target data
signal.
The signal receiving apparatus estimates a soft decision decoding
metric parameter, e.g., noise variance, a shape parameter .alpha.
of a complex-generalized Gaussian (CGG) probability density
function (PDF) and a scale parameter .beta. of the CGG PDF, and/or
the like based on the RE group#1-received signal from which the
target data signal is canceled at operation 717, and proceeds to
operation 719. Here, the CGG PDF is a typical non-Gaussian PDF.
If the signal receiving apparatus calculates the LLR based on the
Gaussian PDF, the soft decision decoding metric parameter estimated
at operation 717 may be the noise variance. If the signal receiving
apparatus calculates the LLR based on the non-Gaussian PDF, the
soft decision decoding metric parameter estimated at operation 717
may be the parameters of the CGG PDF, i.e., the shape parameter
.alpha. and the scale parameter .beta. of the CGG PDF.
The signal receiving apparatus calculates a soft decision decoding
metric, i.e., an LLR, for the received signal based on the
estimated soft decision decoding metric parameter at operation
719.
The signal receiving apparatus detects a received signal which
corresponds to the RE group#2 from the received signal at operation
721, and proceeds to operation 723. For convenience, the received
signal which corresponds to the RE group#2 will be referred to as
`RE group#2-received signal`. As described above, the RE group#2
includes the REs, and there is the possibility that the signal
received through the REs is affected by the boosted interference
signal. So, the RE group#2 includes REs in which a CRS transmitted
by a serving cell to which the signal receiving apparatus belong,
i.e., a target CRS is received.
However, there is a high possibility that a characteristic of an
interference signal which affects the target CRS is significantly
different from a characteristic of an interference signal which
affects a target data signal. The reason is that location of a
reference signal is determined in order that the reference signal
does not collide with a boosted interference signal for preventing
distortion of the reference signal in most standards supporting an
OFDMA scheme. So, a process similar to a process of the RE group #1
may be performed on the RE group #2 to estimate a characteristic of
an interference signal which affects the REs included in the RE
group #2 in which the data signal is received.
That is, the signal receiving apparatus cancels a target data
signal from the RE group#2-received signal at operation 723, and
proceeds to operation 725. The signal receiving apparatus estimates
a soft decision decoding metric parameter, e.g., noise variance, a
shape parameter .alpha. of a CGG PDF and a scale parameter .beta.
of the CGG PDF, and/or the like based on the RE group#2-received
signal from which the target data signal is canceled at operation
725, and proceeds to operation 727. If the signal receiving
apparatus calculates the LLR based on the Gaussian PDF, the soft
decision decoding metric parameter estimated at operation 725 may
be the noise variance. If the signal receiving apparatus calculates
the LLR based on the non-Gaussian PDF, the soft decision decoding
metric parameter estimated at operation 725 may be the parameters
of the CGG PDF, i.e., the shape parameter .alpha. and the scale
parameter .beta. of the CGG PDF.
The signal receiving apparatus calculates a soft decision decoding
metric, i.e., an LLR for the received signal based on the estimated
soft decision decoding metric parameter at operation 727.
Although FIG. 7 illustrates another example of a process of
generating a soft decision decoding metric in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure, various
changes could be made to FIG. 7. For example, although shown as a
series of operations, various operations in FIG. 7 could overlap,
occur in parallel, occur in a different order, or occur multiple
times.
Meanwhile, the RE group#2-received signal as described in FIG. 7
may be affected by a relatively strong-boosted interference signal,
or may be affected by a relatively weak-boosted interference
signal. So, there is a high possibility that a non-Gaussian
characteristic of an interference signal occurs for the RE
group#2-received signal.
So, it may be more advantageous that the signal receiving apparatus
calculates the LLR for the RE group#2-received signal based on the
non-Gaussian PDF compared to a case of calculating the LLR based on
the Gaussian PDF in an aspect of performance improvement. Even
though there is more advantageous aspect of performance
improvement, the signal receiving apparatus may calculate the LLR
based on the Gaussian PDF, not the non-Gaussian PDF for decreasing
implementation complexity.
As described above, the signal receiving apparatus may generate a
soft decision decoding metric by applying different Gaussian PDFs,
i.e., different soft decision decoding metric generating scheme to
the RE group #1 and the RE group #2.
As described above, in an embodiment of the present disclosure, REs
used in a communication system are generated as RE groups based on
a predetermined criterion, and PDFs applied to the RE groups are
determined based on a characteristic of the RE groups. The
predetermined criterion may be, for example, an interference
characteristic, and/or the like. So, an embodiment of the present
disclosure may calculate an LLR which is optimal for a
corresponding RE. An RE grouping process of generating REs as RE
groups and an operation of determining a soft decision decoding
metric generating scheme applied to a corresponding RE group will
be described below, and a detailed description thereof will be
omitted herein.
As described above, an embodiment of the present disclosure
proposes a scheme of calculating a soft decision decoding metric by
applying an appropriate soft decision decoding metric generating
scheme to each RE group, so a scheme of estimating an interference
signal and a scheme of generating a soft decision decoding metric,
e.g., a scheme of calculating an LLR are similar for each
group.
So, an interference signal estimating scheme and an LLR calculating
scheme proposed in an embodiment of the present disclosure will be
described using, for example, an RE group #1, i.e., an RE group
including REs which are not affected by a boosted interference
signal.
If it is assumed that the kth received signal as a RE group
#1-received signal among total received signals is y[k], a received
signal after a target data signal is canceled from the kth received
signal, i.e., a signal including an interference signal and
background noise may be expressed as Equation 1. {circumflex over
(z)}[k]=y[k]-H[k]s[k] [Equation 1]
In Equation 1, {circumflex over (z)}[k] denotes the received signal
after the target data signal is canceled from the kth received
signal, H[k] denotes a fading channel estimation value, and s[k]
denotes a hard decision (or soft decision) value of y[k].
So, a signal receiving apparatus may estimate a characteristic of
an interference signal based on {circumflex over (z)}[k]. If the
signal receiving apparatus calculates an LLR on an assumption that
{circumflex over (z)}[k] is a Gaussian random variable, the signal
receiving apparatus needs to estimates variance for {circumflex
over (z)}[k].
If the signal receiving apparatus calculates an LLR based on a CGG
PDF on an assumption that {circumflex over (z)}[k] is a
non-Gaussian random variable, the signal receiving apparatus needs
to estimate a shape parameter .alpha. and a scale parameter .beta.
of the CGG PDF. A process of estimating the shape parameter .alpha.
and the scale parameter .beta. of the CGG PDF may be expressed as
Equation 2.
.alpha..function..times..times..function..times..times..times..function..-
times..times..times..function..pi..function..times..times..beta..GAMMA..fu-
nction..times..times..alpha..GAMMA..function..times..times..alpha..times..-
times..times..times..function..times..times. ##EQU00001##
In Equation 2, N denotes the number of samples used as interference
signals.
A process of calculating an LLR for a binary channel code
transmitted by a signal transmitting apparatus based on a
characteristic of an interference signal as described above may be
expressed as Equation 3 and Equation 4.
.lamda..function..function..function..times..di-elect
cons..lamda..times..times..function..function..function..times..sigma..di-
-elect
cons..lamda..times..times..function..function..function..times..sig-
ma..times..times..lamda..function..function..function..times..di-elect
cons..lamda..times..times..function..function..function..times..alpha..be-
ta..di-elect
cons..lamda..times..times..function..function..function..times..alpha..be-
ta..times..times. ##EQU00002##
Equation 3 indicates a process of calculating an LLR in a case that
a Gaussian PDF is applied to the RE group #1, and Equation 4
indicates a process of calculating an LLR in a case that a CGG PDF
is applied to the RE group #1. That is,
L.sub.k,.lamda..sup.G(y[k],H[k]) denotes the LLR calculated in the
case that the Gaussian PDF is applied to the RE group #1, and
L.sub.k,.lamda..sup.CGG(y[k],H[k]) denotes the LLR calculated in
the case that the CGG PDF is applied to the RE group #1.
The Gaussian PDF may be expressed as Equation 5.
.function..function..sigma..pi..sigma..times..function..sigma..times..tim-
es. ##EQU00003##
The CGG PDF may be expressed as Equation 6.
.function..function..alpha..beta..alpha..times..pi..beta..times..GAMMA..f-
unction..times..times..alpha..times..function..beta..alpha..times..times.
##EQU00004##
The LLR calculating scheme as described above may be simply
expanded to a likelihood vector for a non-binary channel code.
Meanwhile, an RE grouping process in a communication system
according to an embodiment of the present disclosure will be
described below.
An example of a process of performing an RE grouping process in a
signal receiving apparatus in a communication system supporting an
OFDMA scheme according to an embodiment of the present disclosure
will be described with reference to FIGS. 8A and 8B.
FIGS. 8A and 8B schematically illustrate an example of a process of
performing an RE grouping process in a signal receiving apparatus
in a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure.
Referring to FIGS. 8A and 8B, it will be noted that a process of
performing an RE grouping process in a signal receiving apparatus
as shown in FIG. 8 is a process of performing an RE grouping
process based on the number of CRS ports.
If the communication system supporting the OFDMA scheme is, for
example, an LTE mobile communication system, information about the
number of CRS ports for an interference CRS signal is provided to a
signal receiving apparatus, e.g., a UE. So, the signal receiving
apparatus may generate REs which may be affected by a CRS as a
separate RE group based on the information about the number of CRS
ports. For example, in an LTE mobile communication system
supporting a Release 12 LTE standard, a base station provides UE
with information about the number of CRS ports for an interference
CRS signal.
A RE grouping process in a case that a maximum value of the number
of CRS ports for an interference CRS signal is 1 or 2 is shown in
FIG. 8A.
A RE grouping process in a case that a maximum value of the number
of CRS ports for an interference CRS signal is 4 is shown in FIG.
8B.
In a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure, information about the
number of CRS ports for an interference CRS signal is not provided
to a signal receiving apparatus, e.g., a UE, the signal receiving
apparatus performs an RE grouping process on an assumption that the
number of CRS ports for the interference CRS signal is 2 or 4. Even
though the signal receiving apparatus performs the RE grouping
process on the assumption that the number of CRS ports for the
interference CRS signal is 4, performance degradation hardly
occurs.
An example of a process of performing an RE grouping process in a
signal receiving apparatus in a communication system supporting an
OFDMA scheme according to an embodiment of the present disclosure
has been described with reference to FIGS. 8A and 8B, and another
example of a process of performing an RE grouping process in a
signal receiving apparatus in a communication system supporting an
OFDMA scheme according to an embodiment of the present disclosure
will be described with reference to FIGS. 9A to 9C.
FIGS. 9A to 9C schematically illustrate another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIGS. 9A to 9C, it will be noted that a process of
performing an RE grouping process by a signal receiving apparatus
as shown in FIGS. 9A to 9C is a process of performing an RE
grouping process by a signal receiving apparatus in a case that
each cell changes location of an RE through which a reference
signal, e.g., a pilot signal is transmitted on a time axis.
In most standards supporting an OFDMA scheme such as an LTE,
location at which reference signals are transmitted is set such
that collision among reference signals, e.g., pilot signals does
not occur among neighbor cells, an embodiment of the present
disclosure assumes a case that each cell changes location of an RE
at which a reference signal is transmitted on a time axis.
So, an embodiment of the present disclosure may generate an RE
group which may be affected by the reference signal with various
forms as shown as FIGS. 9A to 9C.
Another example of a process of performing an RE grouping process
in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIGS. 9A to
9C, and still another example of a process of performing an RE
grouping process in a signal receiving apparatus in a communication
system supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 10.
FIG. 10 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 10, it will be noted that a process of performing
an RE grouping process in a signal receiving apparatus as shown in
FIG. 10 is a process of performing an RE grouping process in a
signal receiving apparatus in a case that a transmission mode (TM)
in which a demodulation reference signal (DM-RS) is transmitted is
included in an interference signal.
If the communication system supporting the OFDMA scheme is, for
example, an LTE mobile communication system, information related to
an interference signal is provided to a signal receiving apparatus,
e.g., a UE. So, the signal receiving apparatus may know information
about the TM in which the DM-RS is transmitted. The information
related to the interference signal provided in the LTE mobile
communication system will be described below, and a detailed
description thereof will be omitted herein.
So, in an embodiment of the present disclosure, an RE group which
may be affected by the reference signal may be generated based on a
TM in which a DM-RS is transmitted as shown in FIG. 10.
Meanwhile, if a TM in which a DM-RS is transmitted is not included
in an interference signal, a signal receiving apparatus may perform
an RE grouping process based on an RE grouping process as described
in FIGS. 8A and 8B, i.e., an RE grouping process which is based on
the number of CRS ports. This RE grouping process may be performed
if there is a case that a DM-RS affects an RE through which a
target data signal is transmitted, and the signal receiving
apparatus performs an RE grouping process based on location of an
interference CRS and location at which the DM-RS is
transmitted.
Still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIG. 10,
and still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 11.
FIG. 11 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 11, it will be noted that a process of performing
an RE grouping process in a signal receiving apparatus as shown in
FIG. 10 is a process of performing an RE grouping process in a
signal receiving apparatus in a case that a TM in which a channel
state information reference signal (CSI-RS) is transmitted is
included in an interference signal.
If the communication system supporting the OFDMA scheme is, for
example, an LTE mobile communication system, information related to
an interference signal is provided to a signal receiving apparatus,
e.g., a UE. So, the signal receiving apparatus may know information
about the TM in which the CSI-RS is transmitted.
So, in an embodiment of the present disclosure, an RE group which
may be affected by the reference signal may be generated based on a
TM in which a CSI-RS is transmitted as shown in FIG. 11.
Still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIG. 11,
and still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 12.
FIG. 12 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 12, it will be assumed that a communications
system supporting an OFDMA scheme is an LTE mobile communication
system. Further, a signal receiving apparatus, e.g., a UE may
receive information related to an interference signal form a signal
transmitting apparatus, e.g., a base station.
The UE receives information related to an interference signal,
e.g., a RadioResourceConfigDedicated information element (IE) from
a base station.
The RadioResourceConfigDedicated IE includes various fields,
particularly, in an embodiment of the present disclosure, an RE
group is generated based on a NeighCellsInfo-r12 field among the
fields included in the RadioResourceConfigDedicated IE. The
NeighCellsInfo-r12 field may be expressed as Table 1.
TABLE-US-00001 TABLE 1 NeighCellsInfo-r12 ::= SEQUENCE {
physCellId-r12 PhysCellId, p-b-r12 INTEGER (0..3),
crs-PortsCount-r12 ENUMERATED {n1, n2, n4, spare},
mbsfn-SubframeConfig-r12 MBSFN-SubframeConfigList OPTIONAL, -- Need
ON p-aList-r12 SEQUENCE (SIZE (1..maxP-a-PerNeighCell-r12)) OF P-a,
transmissionModeList-r12 BIT STRING (SIZE (8)),
resAllocGranularity-r12 INTEGER (1..4), ... }
In Table 1, the NeighCellsInfo-r12 field includes secondary
information which is used by a UE thereby interference of a
neighbor cell is canceled and suppressed. If the NeighCellsInfo-r12
field exists for a neighbor cell, the UE assumes that transmission
parameters listed in sub-fields included in the NeighCellsInfo-r12
field are used by the neighbor cell. If the NeighCellsInfo-r12
field exists for a neighbor cell, the UE assumes that the neighbor
cell has a sub-frame and a system frame number (SFN) which are
synchronized with a serving cell, a system bandwidth which is equal
to a system bandwidth of the serving cell, a uplink/downlink
sub-frame configuration and a specific sub-frame configuration
which are identical to a uplink/downlink sub-frame configuration
and a specific sub-frame configuration of the serving cell, and a
cyclic prefix length which is equal to a cyclic prefix length of
the serving cell.
In Table 1, physCellld-r12 indicates a cell ID of a neighbor cell.
In the LTE mobile communication system, a CRS is shifted by a
preset offset value on a frequency axis according to a cell ID.
Here, the offset value applied to the corresponding CRS which is
based on the cell ID may be expressed as Equation 7.
v.sub.shift=mod(Cell ID,6) [Equation 7]
In Equation 7, vshift denotes an offset value applied to a
corresponding CRS, and denotes an offset on a frequency axis which
is based on a preset reference CRS. In Equation 7, mod denotes a
modulo calculation, and a Cell ID denotes a cell ID of a
corresponding cell.
For example, if the cell ID of the corresponding cell is 100,
vshift is 4, and, if the number of CRS ports is 1, a CRS as shown
in FIG. 12 is transmitted.
Meanwhile, crs-PortsCount-r12 among sub-fields included in the
NeighCellsInfo-r12 field among fields included in the
RadioResourceConfigDedicated IE indicates the number of CRS ports
of a neighbor cell. A CRS structure according to the number of CRS
ports will be described with reference to FIGS. 13 to 15, and a
detailed description will be omitted herein.
So, CRS location for the interference signal transmitted in the
corresponding cell may be detected based on the physCellld-r12 and
crs-PortsCount-r12.
A process of performing an RE grouping process in a UE as shown in
FIG. 12 will be described with reference to, for example, a release
12 (Rel. 12) LTE mobile communication system.
In a Rel. 12 LTE mobile communication system, a
RadioResourceConfigDedicated IE may include up to 8
NeighCellsInfo-r12 fields. So, if a base station transmits a
RadioResourceConfigDedicated IE including 8 NeighCellsInfo-r12
fields, the UE may acquire location information for 8 CRSs.
So, the UE generates REs in which there is no possibility of being
affected by an interference CRS as an RE group #1 and generates REs
in which there is a possibility of being affected by the
interference CRS as an RE group #2 based on location information
for the acquired 8 CRSs.
Still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIG. 12,
and an example of a CRS structure according to the number of CRS
ports in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure will be
described with reference to FIG. 13.
FIG. 13 schematically illustrates an example of a CRS structure
according to the number of CRS ports in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 13, a CRS structure according to the number of
CRS ports as shown in FIG. 13 indicates a CRS structure according
to the number of CRS ports in a case that one antenna port is used.
Further, the CRS structure according to the number of CRS ports as
shown in FIG. 13 indicates a CRS structure according to the number
of CRS ports in a case that the number of CRS ports is 1.
An example of a CRS structure according to the number of CRS ports
in a communication system supporting an OFDMA scheme according to
an embodiment of the present disclosure has been described with
reference to FIG. 13, and another example of a CRS structure
according to the number of CRS ports in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 14.
FIG. 14 schematically illustrates another example of a CRS
structure according to the number of CRS ports in a communication
system supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 14, a CRS structure according to the number of
CRS ports as shown in FIG. 14 indicates a CRS structure according
to the number of CRS ports in a case that two antenna ports are
used. Further, the CRS structure according to the number of CRS
ports as shown in FIG. 14 indicates a CRS structure according to
the number of CRS ports in a case that the number of CRS ports is
2.
Another example of a CRS structure according to the number of CRS
ports in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure has been
described with reference to FIG. 14, and still another example of a
CRS structure according to the number of CRS ports in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure will be described with
reference to FIG. 15.
FIG. 15 schematically illustrates still another example of a CRS
structure according to the number of CRS ports in a communication
system supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 15, a CRS structure according to the number of
CRS ports as shown in FIG. 15 indicates a CRS structure according
to the number of CRS ports in a case that four antenna ports are
used. Further, the CRS structure according to the number of CRS
ports as shown in FIG. 15 indicates a CRS structure according to
the number of CRS ports in a case that the number of CRS ports is
4.
Still another example of a CRS structure according to the number of
CRS ports in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure has been
described with reference to FIG. 15, and still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure will be
described with reference to FIG. 16.
FIG. 16 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 16, it will be assumed that a target signal,
i.e., a target CRS 1611 is a target signal in a case that a Cell ID
is 100, the number of CRS ports is 1, and the number of orthogonal
frequency division multiplexing (OFDM) symbols allocated to a
physical downlink control channel (PDCCH) is 3. Here, information
about the target signal may be acquired through a physical control
format indicator channel (PCFICH).
It will be assumed that there are two interference signals, i.e.,
two interference CRSs, i.e., an interference CRS 1613 received from
a neighbor cell of which a cell ID is 101 and a CRS 1615 received
from a neighbor cell of which a cell ID is 105. Here, the
interference CRS 1613 is a CRS in a case that a field value of a
physCellld-r12 field included in a NeighCellsInfo-r12 is 101, and a
field value of a crs-PortsCount-r12 sub-field included in the
physCellld-r12 field is 2 (physCellld-r12=[101],
crs-PortsCount-r12=[2]). Here, the interference CRS 1615 is a CRS
in a case that a field value of a physCellld-r12 field included in
a NeighCellsInfo-r12 is 105, and a field value of a
crs-PortsCount-r12 sub-field included in the physCellld-r12 field
is 2 (physCellld-r12=[105], crs-PortsCount-r12=[2]).
So, a UE which is based on the target CRS 1611, the interference
CRS 1613, and the interference CRS 165 may generate an RE group#1
as a group including REs in which there is no possibility of being
affected by the interference CRS 1613 and the interference CRS 165
and an RE group#2 as a group including REs in which there is a
possibility of being affected by the interference CRS 1613 and the
interference CRS 165.
As shown in FIG. 16, in a case of being based on the target CRS
1611, the interference CRS 1613, and the interference CRS 165,
REs#1 to #12, an RE#15, an RE#20, REs#23 to #47, an RE#52, REs#57
to #92, an RE#95, an RE#100, and REs#103 to #126 among total 126
REs from REs#1 to #126 are included in the RE group#1.
In a case of being based on the target CRS 1611, the interference
CRS 1613, and the interference CRS 165, an RE#13, an RE#14, an
RE#16, an RE#17, an RE#18, an RE#19, an RE#21, an RE#22, an RE#48,
an RE#49, an RE#50, an RE#51, an RE#53, an RE#54, an RE#55, an
RE#56, an RE#93, an RE#94, an RE#96, an RE#97, an RE#98, an RE#99,
an RE#101, and an RE#102 among the total 126 REs from the REs#1 to
#126 are included in the RE group#2.
Still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIG. 16,
and still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 17.
FIG. 17 schematically illustrates still another example of a
process of performing an RE grouping process in a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure.
Referring to FIG. 17, a signal receiving apparatus, e.g., a UE may
identify an RE which is affected by an interference CRS based on
CRS location. So, the signal receiving apparatus may generate an RE
group, i.e., an RE group #2 such that all REs which are affected by
an interference CRS are included in the RE group.
Firstly, it will be assumed that a target signal is a target signal
in a case that a cell ID is 100, the number of CRS ports is 1, and
the number of OFDM symbols allocated to a PDCCH is 3. Here,
information about the target signal may be acquired through a
PCFICH.
In this case, REs included in an RE group #1 including REs which
are not affected by a boosted interference signal are REs#1 to #12,
REs #23 to #46, REs#69 to #92, and REs#103 to #126.
Further, REs included in an RE group #2 including REs which are
affected by a boosted interference signal are REs#13 to #22, REs
#47 to #68, and REs#93 to #102.
Still another example of a process of performing an RE grouping
process in a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure has been described with reference to FIG. 17,
and performance in a case that an RE grouping process is applied in
a communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure will be described with
reference to FIG. 18.
FIG. 18 schematically illustrates performance in a case that an RE
grouping process is applied in a communication system supporting an
OFDMA scheme according to an embodiment of the present
disclosure.
Referring to FIG. 18, it will be understood that performance 1813
in a case that an RE grouping process according to an embodiment of
the present disclosure is applied is improved by about 2 [dB]
compared to performance 1811 in a case that the RE grouping process
according to an embodiment of the present disclosure is not
applied.
Performance in a case that an RE grouping process is applied in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure has been described with
reference to FIG. 18, and examples of an inner structure of a
signal receiving apparatus in a communication system supporting an
OFDMA scheme according to an embodiment of the present disclosure
will be described with reference to FIGS. 19 to 22.
Prior to description of FIGS. 19 to 22, variables and computations
used in FIGS. 19 to 22 will be defined as the following.
(1) Y.sub.k
Y.sub.k denotes the kth received symbol vector.
(2) Y.sub.i[k]
Y.sub.i[k] denotes the kth symbol received through the ith
reception antenna.
(3) {tilde over (Y)}.sub.k
{tilde over (Y)}.sub.k denotes an output value of a
CRS-interference cancellation (IC) unit for Y.sub.k.
(4) {tilde over (Y)}.sub.i[k]
{tilde over (Y)}.sub.i[k] denotes an output value of a CRS-IC unit
for Y.sub.i[k].
(5) R[k]
R[k] denotes an output value of a minimum mean square
error-interference rejection combining (MMSE-IRC) unit for {tilde
over (Y)}.sub.k.
(6) H.sub.k
H.sub.k denotes a fading channel estimation vector for the kth
received symbol.
(7) H.sub.ij[k]
H.sub.ij[k] denotes a fading channel estimation vector between the
jth transmission antenna and the ith reception antenna for the kth
received symbol.
(8) s[k]
s[k] denotes the kth transmission symbol.
(9) nk
nk denotes a noise component vector of the kth received symbol.
(10) ni[k]
ni[k] denotes a noise component of the kth received symbol received
through the ith reception antenna.
(11) {tilde over (.sigma.)}.sub.i.sup.2
{tilde over (.sigma.)}.sub.i.sup.2 denotes noise variance estimated
from {tilde over (Y)}.sub.i[k].
(12) A.sub.i.sup..lamda.
A.sub.i.sup..lamda. denotes a set of candidate modulation symbols
of which the .lamda.th bit is i.
(13) A.sub.0.orgate.A.sub.1
A.sub.0.orgate.A.sub.1 denotes a set of all candidate modulation
symbols.
(14) CN(a,b)
CN(a,b) denotes a complex Gaussian random variable of which mean is
a and variance is b.
(15) (a).sup.H
(a).sup.H denotes Hermitian (conjugate transpose) calculation of
a.
(16) E{a}
E{a} denotes calculation of calculating mean of a.
Prior to description of FIGS. 19 to 22, it will be noted that
Equations used in FIGS. 19 to 22 are generated on an assumption
that the number of transmission antennas is 1, and the number of
reception antennas is 2. That is, if the number of transmission
antennas is greater than 1, or the number of reception antennas is
1 or greater than 2, Equations used in FIGS. 19 to 22 may be
modified corresponding to this.
Another example of an inner structure of a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure will be
described with reference to FIG. 19.
FIG. 19 schematically illustrates another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 19, a signal receiving apparatus 1900 may be, for
example, a UE, and includes a CRS-interference cancellation (IC)
unit 1911, a channel estimator #1 1913, a minimum mean square
error-interference rejection combining (MMSE-IRC) unit 1915, a
channel estimator #2 1917, an LLR generator 1919, and a channel
decoder 1921.
Firstly, Y.sub.k as the kth received symbol vector is inputted to
each of the CRS-IC unit 1911 and the channel estimator #1 1913.
Here, Y.sub.k may be expressed as Equation 8.
.function..function..times..times. ##EQU00005##
The channel estimator #1 1913 estimates a channel based on Y.sub.k
to generate a channel estimation value, e.g., a channel estimation
value in which ICI is considered, and outputs the channel
estimation value to the CRS-IC unit 1911.
The CRS-IC unit 1911 performs a CRC-IC operation based on Y.sub.k
and the channel estimation value outputted from the channel
estimator #1 1913 to generate a result value {tilde over
(Y)}.sub.k, and outputs the result value {tilde over (Y)}.sub.k to
each of the MMSE-IRC unit 1915 and the channel estimator #2
1917.
Here, {tilde over (Y)}.sub.k may be expressed as Equation 9.
.function..function..times..times. ##EQU00006##
The channel estimator #2 1917 estimates a channel based on {tilde
over (Y)}.sub.k outputted from the CRS-IC unit 1911 to generate a
channel estimation value, e.g., a channel estimation value in which
a target signal is considered, and outputs the channel estimation
value to the MMSE-IRC unit 1915.
The MMSE-IRC unit 1915 performs an MMSE-IRC operation based on
{tilde over (Y)}.sub.k outputted from the CRS-IC unit 1911 and the
channel estimation value outputted from the channel estimator #2
1917 to generate a result value R[k], and outputs the result value
R[k] to the LLR generator 1919. R[k] may be expressed as Equation
10.
.times..function..times..function..times..function..mu..function..times..-
times..times..times..times..function..times..function..eta..times..times..-
times..times..function..function..times..times..function..function..eta..d-
i-elect cons..times..function..function..times..di-elect
cons..times..function..function..times..times..function..eta..times..time-
s..times..times..times..times..times..times..times..di-elect
cons..times..times..times..times..times..times..eta..function..eta..times-
..times..times..mu..times..about..times..function..function..times..sigma.-
.function..times..sigma..times..times..function..function..times..function-
..function..times..function..times..times..mu..function..function..times..-
function..function..times..function..times..times. ##EQU00007##
In Equation 10, Cov(a).sub.Group index.sup.RB index denotes a
computation for calculating a variation matrix using samples within
a given group index and RB index. In Equation 10, .eta.k denotes a
noise vector value estimated from {tilde over (Y)}.sub.k. In
Equation 10, N.sub.Group index.sup.RB index denotes the number of
RE samples within the given group index and RB index. In Equation
10, V.sub.Group index.sup.RB index denotes a set of RE indexes
within the given group index and RB index.
Further, it will be noted that R[k] as expressed in Equation 10 is
R[k] in a case of single input multi-output (SIMO) (a case that the
number of transmission antennas is 1 and the number of reception
antennas is 2).
The MMSE-IRC unit 1915 performs a variation matrix of noise per RE
group, and uses a data RE upon performing noise variation
estimating operation. So, the signal receiving apparatus 1900 needs
to perform a hard decision operation on a received signal.
The LLR generator 1919 generates an LLR based on R[k] outputted
from the MMSE-IRC unit 1915 and outputs the generated LLR to the
channel decoder 1921. Here, the LLR may be expressed as Equation
11.
.lamda..function..function..function..apprxeq..sigma..times..di-elect
cons..lamda..times..function..function..times..di-elect
cons..lamda..times..function..function..times..times..times.
##EQU00008##
In Equation 11, .sigma..sub.k.sup.2=(w.sub.1[k]).sup.2{tilde over
(.sigma.)}.sub.1.sup.2+(w.sub.2[k]).sup.2{tilde over
(.sigma.)}.sub.2.sup.2.
The channel decoder 1921 performs a channel decoding operation
based on the LLR outputted from the LLR generator 1919.
Although the CRS-IC unit 1911, the channel estimator #1 1913, the
MMSE-IRC unit 1915, the channel estimator #2 1917, the LLR
generator 1919, and the channel decoder 1921 are described as
separate units in the signal receiving apparatus 1900 in FIG. 19,
it is to be understood that the signal receiving apparatus 1900 may
be implemented with a form into which at least two of the CRS-IC
unit 1911, the channel estimator #1 1913, the MMSE-IRC unit 1915,
the channel estimator #2 1917, the LLR generator 1919, and the
channel decoder 1921 are incorporated. The signal receiving
apparatus 1900 may be implemented with one processor. Another
example of an inner structure of a signal receiving apparatus in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure has been described with
reference to FIG. 19, and still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure will be described with reference to FIG. 20.
FIG. 20 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 20, a signal receiving apparatus 2000 includes a
CRS-IC unit 2011, a channel estimator #1 2013, an MMSE-IRC unit
2015, a channel estimator #2 2017, an LLR generator 2019, and a
channel decoder 2021.
Firstly, Y.sub.k as the kth received symbol vector is inputted to
each of the CRS-IC unit 2011 and the channel estimator #1 2013.
Here, Y.sub.k may be expressed as Equation 8.
The channel estimator #1 2013 estimates a channel based on Y.sub.k
to generate a channel estimation value, e.g., a channel estimation
value in which ICI is considered, and outputs the channel
estimation value to the CRS-IC unit 2011.
The CRS-IC unit 2011 performs a CRC-IC operation based on Y.sub.k
and the channel estimation value outputted from the channel
estimator #1 2013 to generate a result value {tilde over
(Y)}.sub.k, and outputs the result value {tilde over (Y)}.sub.k to
each of the MMSE-IRC unit 2015 and the channel estimator #2 2017.
Here, {tilde over (Y)}.sub.k may be expressed as Equation 9.
The channel estimator #2 2017 estimates a channel based on {tilde
over (Y)}.sub.k outputted from the CRS-IC unit 2011 to generate a
channel estimation value, e.g., a channel estimation value in which
a target signal is considered, and outputs the channel estimation
value to the MMSE-IRC unit 2015.
The MMSE-IRC unit 2015 performs an MMSE-IRC operation based on
{tilde over (Y)}.sub.k outputted from the CRS-IC unit 2011 and the
channel estimation value outputted from the channel estimator #2
2017 to generate a result value R[k], and outputs the result value
R[k] to the LLR generator 2019. R[k] may be expressed as Equation
12.
.times..function..times..function..times..function..mu..function..times..-
times..times..times..times..times..function..times..function..function..fu-
nction..times..times..times..function..function..function..function..times-
..function..times..times..di-elect
cons..times..times..times..times..times..times..times..times..times..time-
s..mu..times..about..times..function..function..times..sigma..function..ti-
mes..sigma..times..times..function..function..times..function..function..t-
imes..function..times..times..mu..function..function..times..function..fun-
ction..times..function..times..times. ##EQU00009##
It will be noted that R[k] as expressed in Equation 12 is R[k] in a
case of, for example, SIMO (a case that the number of transmission
antennas is 1, and the number of reception antennas is 2). As
expressed in Equation 12, the MMSE-IRC unit 2015 may estimate a
covariance matrix using only a CRS, so the MMSE-IRC unit 2015 does
not need an RB index and a group index. In Equation 12, ck denotes
the kth transmitted CRS symbol. In Equation 12, NCRS denotes the
number of CRS symbols. In Equation 12, Cov(a) denotes computation
of calculating a covariance matrix for a.
The LLR generator 2019 generates an LLR based on R[k] outputted
from the MMSE-IRC unit 2015, and outputs the generated LLR to the
channel decoder 2021. Here, the LLR may be expressed as Equation
13.
.lamda..function..function..function..times..times..times..times..apprxeq-
..sigma..times..times..times..times..times..times..di-elect
cons..lamda..times..function..function..times..di-elect
cons..lamda..times..function..function..times..times..times.
##EQU00010##
In Equation 13, L.sub.k,.lamda..sup.G(R[k],a[k],RB index,Group
index) denotes an LLR for the .lamda.th bit for given R[k], a[k],
RB index, and Group index. In Equation 13, .sigma..sub.Group
index.sup.RB index denotes an estimation value of noise variance
within the given Group index and RB index. In Equation 13, ck
denotes the kth transmitted CRS symbol. In Equation 13, NCRS
denotes the number of CRS symbols. In Equation 13, Cov(a) denotes
computation of calculating a covariance matrix for a.
The LLR generator 2019 estimates noise variance per RE group for
R[k] outputted from the MMSE-IRC unit 2015, and calculates an LLR
based on the estimated noise variance per RE group. Here, an
operation of estimating the noise variance per RE group has a form
of duplicated calculation, so the operation may be implemented with
a complexity almost similar to a general noise variance estimating
operation.
The channel decoder 2021 performs a channel decoding operation
based on the LLR outputted from the LLR generator 2019.
Although the CRS-IC unit 2011, the channel estimator #1 2013, the
MMSE-IRC unit 2015, the channel estimator #2 2017, the LLR
generator 2019, and the channel decoder 2021 are described as
separate units in the signal receiving apparatus 2000 in FIG. 20,
it is to be understood that the signal receiving apparatus 2000 may
be implemented with a form into which at least two of the CRS-IC
unit 2011, the channel estimator #1 2013, the MMSE-IRC unit 2015,
the channel estimator #2 2017, the LLR generator 2019, and the
channel decoder 2021 are incorporated. The signal receiving
apparatus 2000 may be implemented with one processor.
Another example of an inner structure of a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure has been
described with reference to FIG. 20, and still another example of
an inner structure of a signal receiving apparatus in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure will be described with
reference to FIG. 21.
FIG. 21 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 21, a signal receiving apparatus 2100 includes a
CRS-IC unit 2111, a channel estimator #1 2113, an MMSE-IRC unit
2115, a channel estimator #2 2117, an LLR generator 2119, and a
channel decoder 2121.
Firstly, Y.sub.k as the kth received symbol vector is inputted to
each of the CRS-IC unit 2111 and the channel estimator #1 2113.
Here, Y.sub.k may be expressed as Equation 8.
The channel estimator #1 2113 estimates a channel based on Y.sub.k
to generate a channel estimation value, e.g., a channel estimation
value in which ICI is considered, and outputs the channel
estimation value to the CRS-IC unit 2111.
The CRS-IC unit 2111 performs a CRC-IC operation based on Y.sub.k
and the channel estimation value outputted from the channel
estimator #1 2113 to generate a result value {tilde over
(Y)}.sub.k, and outputs the result value {tilde over (Y)}.sub.k to
each of the MMSE-IRC unit 2115 and the channel estimator #2 2117.
Here, {tilde over (Y)}.sub.k may be expressed as Equation 9.
The channel estimator #2 2117 estimates a channel based on {tilde
over (Y)}.sub.k outputted from the CRS-IC unit 2111 to generate a
channel estimation value, e.g., a channel estimation value in which
a target signal is considered, and outputs the channel estimation
value to the MMSE-IRC unit 2115.
The MMSE-IRC unit 2115 performs an MMSE-IRC operation based on
{tilde over (Y)}.sub.k outputted from the CRS-IC unit 2111 and the
channel estimation value outputted from the channel estimator #2
2117 to generate a result value R[k], and outputs the result value
R[k] to the LLR generator 2119. R[k] may be expressed as Equation
14.
.times..function..times..function..times..function..mu..function..times..-
times..times..times..times..times..function..times..function..function..fu-
nction..times..times..times..function..function..function..function..times-
..function..times..times..di-elect
cons..times..times..times..times..times..times..times..times..times..time-
s..mu..times..about..times..function..function..times..sigma..function..ti-
mes..sigma..times..times..function..function..times..function..function..t-
imes..function..times..times..mu..function..function..times..function..fun-
ction..times..function..times..times. ##EQU00011##
It will be noted that R[k] as expressed in Equation 14 is R[k] in a
case of, for example, SIMO (a case that the number of transmission
antennas is 1, and the number of reception antennas is 2).
The LLR generator 2119 generates an LLR based on R[k] outputted
from the MMSE-IRC unit 2115, and outputs the generated LLR to the
channel decoder 2121. Here, the LLR may be expressed as Equation
15.
.lamda..function..function..function..times..times..times..times..apprxeq-
..beta..times..times..times..times..times..di-elect
cons..lamda..times..function..function..times..di-elect
cons..lamda..times..function..function..times..alpha..times..times..times-
..times..times..times..times..times..times..alpha..times..times..times..ti-
mes..function..times..times..times..times..times..times..times..times..tim-
es..times..beta..times..times..times..times..GAMMA..function..alpha..GAMMA-
..function..alpha..times..times..times..times..times..times..times..times.-
.times..times..times..times..times..times..times..times..times..times..tim-
es..times..times..times..times..function..times..times..times..times..time-
s..times..times..times..times..times..times..times..times..times..times..t-
imes..times..function..times..times..times..function..di-elect
cons..times..function..function..times..function..function..times..times.
##EQU00012##
In Equation 15, .alpha..sub.Group index.sup.RB index denotes a
shape parameter of CGG PDF which is estimated using an RE sample
within a given group index and RB index. In Equation 15,
.beta..sub.Group index.sup.RB index denotes a scale parameter of
CGG PDF which is estimated using an RE sample within a given group
index and RB index.
The LLR generator 2119 estimates noise variance per RE group for
R[k] outputted from the MMSE-IRC unit 2115, and calculates an LLR
based on the estimated noise variance per RE group. Here, an
operation of estimating the noise variance per RE group has a form
of duplicated calculation, so the operation may be implemented with
a complexity almost similar to a general noise variance estimating
operation. As expressed in Equation 15, the LLR generator 2119
needs to perform a calculation such as computation, log( )
computation, .GAMMA.( ) computation, ( ).alpha. computation, and/or
the like upon generating an LLR.
The channel decoder 2121 performs a channel decoding operation
based on the LLR outputted from the LLR generator 2119.
Although the CRS-IC unit 2111, the channel estimator #1 2113, the
MMSE-IRC unit 2115, the channel estimator #2 2117, the LLR
generator 2119, and the channel decoder 2121 are described as
separate units in the signal receiving apparatus 2100 in FIG. 21,
it is to be understood that the signal receiving apparatus 2100 may
be implemented with a form into which at least two of the CRS-IC
unit 2111, the channel estimator #1 2113, the MMSE-IRC unit 2115,
the channel estimator #2 2117, the LLR generator 2119, and the
channel decoder 2121 are incorporated. The signal receiving
apparatus 2100 may be implemented with one processor.
Still another example of an inner structure of a signal receiving
apparatus in a communication system supporting an OFDMA scheme
according to an embodiment of the present disclosure has been
described with reference to FIG. 21, and still another example of
an inner structure of a signal receiving apparatus in a
communication system supporting an OFDMA scheme according to an
embodiment of the present disclosure will be described with
reference to FIG. 22.
FIG. 22 schematically illustrates still another example of an inner
structure of a signal receiving apparatus in a communication system
supporting an OFDMA scheme according to an embodiment of the
present disclosure.
Referring to FIG. 22, a signal receiving apparatus 2200 includes a
CRS-IC unit 2211, a channel estimator #1 2213, an MMSE-IRC unit
2215, a channel estimator #2 2217, an LLR generator 2219, and a
channel decoder 2221.
Firstly, Y.sub.k as the kth received symbol vector is inputted to
each of the CRS-IC unit 2211 and the channel estimator #1 2213.
Here, Y.sub.k may be expressed as Equation 8.
The channel estimator #1 2213 estimates a channel based on Y.sub.k
to generate a channel estimation value, e.g., a channel estimation
value in which ICI is considered, and outputs the channel
estimation value to the CRS-IC unit 2211.
The CRS-IC unit 2211 performs a CRC-IC operation based on Y.sub.k
and the channel estimation value outputted from the channel
estimator #1 2213 to generate a result value {tilde over
(Y)}.sub.k, and outputs the result value {tilde over (Y)}.sub.k to
each of the MMSE-IRC unit 2215 and the channel estimator #2 2217.
Here, {tilde over (Y)}.sub.k may be expressed as Equation 9.
The channel estimator #2 2217 estimates a channel based on {tilde
over (Y)}.sub.k outputted from the CRS-IC unit 2211 to generate a
channel estimation value, e.g., a channel estimation value in which
a target signal is considered, and outputs the channel estimation
value to the MMSE-IRC unit 2215.
The MMSE-IRC unit 2215 performs an MMSE-IRC operation based on
{tilde over (Y)}.sub.k outputted from the CRS-IC unit 2211 and the
channel estimation value outputted from the channel estimator #2
2217 to generate a result value R[k], and outputs the result value
R[k] to the LLR generator 2219. R[k] may be expressed as Equation
14.
The LLR generator 2219 generates an LLR based on R[k] outputted
from the MMSE-IRC unit 2215, and outputs the generated LLR to the
channel decoder 2221. The LLR may be expressed in FIG. 23.
In the LLR as expressed in FIG. 23 compared to an LLR as expressed
in Equation 15,
.GAMMA..function..times..times..alpha..GAMMA..function..times..times..alp-
ha. ##EQU00013## related to .beta..sub.Group index.sup.RB index is
changed to a constant value, and a .alpha..sub.Group index.sup.RB
index value is quantized, so the LLR generator 2219 does not need
to perform a computation such as .GAMMA.( ) computation, ( ).alpha.
computation, and/or the like. For example, .alpha..sub.Group
index.sup.RB index may be quantized as one of 0.5, 1, 1.5, and
2.
The LLR generator 2219 estimates noise variance per RE group for
R[k] outputted from the MMSE-IRC unit 2215, and calculates an LLR
based on the estimated noise variance per RE group. Here, an
operation of estimating the noise variance per RE group has a form
of duplicated calculation, so the operation may be implemented with
a complexity almost similar to a general noise variance estimating
operation. As expressed in Equation 16, the LLR generator 2219
needs to perform a complex calculation such as .GAMMA.( )
computation, ( ).alpha. computation, and/or the like upon
generating an LLR.
The channel decoder 2221 performs a channel decoding operation
based on the LLR outputted from the LLR generator 2219.
Although the CRS-IC unit 2211, the channel estimator #1 2213, the
MMSE-IRC unit 2215, the channel estimator #2 2217, the LLR
generator 2219, and the channel decoder 2221 are described as
separate units in the signal receiving apparatus 2200 in FIG. 22,
it is to be understood that the signal receiving apparatus 2200 may
be implemented with a form into which at least two of the CRS-IC
unit 2211, the channel estimator #1 2213, the MMSE-IRC unit 2215,
the channel estimator #2 2217, the LLR generator 2219, and the
channel decoder 2221 are incorporated. The signal receiving
apparatus 2200 may be implemented with one processor.
Certain aspects of the present disclosure may also be embodied as
computer readable code on a non-transitory computer readable
recording medium. A non-transitory computer readable recording
medium is any data storage device that can store data, which can be
thereafter read by a computer system. Examples of the
non-transitory computer readable recording medium include read only
memory (ROM), random access memory (RAM), CD-ROMs, magnetic tapes,
floppy disks, optical data storage devices, and carrier waves (such
as data transmission through the Internet). The non-transitory
computer readable recording medium can also be distributed over
network coupled computer systems so that the computer readable code
is stored and executed in a distributed fashion. In addition,
functional programs, code, and code segments for accomplishing the
present disclosure can be easily construed by programmers skilled
in the art to which the present disclosure pertains.
It can be appreciated that a method and apparatus according to an
embodiment of the present disclosure may be implemented by
hardware, software and/or a combination thereof. The software may
be stored in a non-volatile storage, for example, an erasable or
re-writable ROM, a memory, for example, a RAM, a memory chip, a
memory device, or a memory integrated circuit (IC), or an optically
or magnetically recordable non-transitory machine-readable (e.g.,
computer-readable), storage medium (e.g., a compact disk (CD), a
digital video disc (DVD), a magnetic disk, a magnetic tape, and/or
the like). A method and apparatus according to an embodiment of the
present disclosure may be implemented by a computer or a mobile
terminal that includes a controller and a memory, and the memory
may be an example of a non-transitory machine-readable (e.g.,
computer-readable), storage medium suitable to store a program or
programs including instructions for implementing various
embodiments of the present disclosure.
The present disclosure may include a program including code for
implementing the apparatus and method as defined by the appended
claims, and a non-transitory machine-readable (e.g.,
computer-readable), storage medium storing the program. The program
may be electronically transferred via any media, such as
communication signals, which are transmitted through wired and/or
wireless connections, and the present disclosure may include their
equivalents.
An apparatus according to an embodiment of the present disclosure
may receive the program from a program providing device which is
connected to the apparatus via a wire or a wireless and store the
program. The program providing device may include a memory for
storing instructions which instruct to perform a content protect
method which has been already installed, information necessary for
the content protect method, and the like, a communication unit for
performing a wired or a wireless communication with a graphic
processing device, and a controller for transmitting a related
program to a transmitting/receiving device based on a request of
the graphic processing device or automatically transmitting the
related program to the transmitting/receiving device.
While the present disclosure has been shown and described with
reference to various embodiments thereof, it will be understood by
those skilled in the art that various changes in form and details
may be made therein without departing from the spirit and scope of
the present disclosure as defined by the appended claims and their
equivalents.
* * * * *